The present invention generally relates to a support system for an automobile power plant and, more particularly, to a support system for supporting an automobile power plant in an engine compartment of the automobile body structure.
It is generally well known that, in an automobile of either a front engine, front wheel drive type or a rear engine, rear wheel drive type, an automobile power plant including an engine, a transmission and a differential gear box is housed in an engine compartment with the axis of rotation of at least the engine extending widthwise of the automobile body structure. As compared with the longitudinal mounting arrangement of the automobile power plant in which the engine is mounted with its axis of rotation extending longitudinally of the body structure, this transverse mounting arrangement is susceptible to a relatively large rolling motion due to abrupt change in torque and/or the traction force resisting against the road resistance. In view of this, a torque rod, i.e., a roll stopper, has been employed to connect the top of the power plant to a partition wall separating the engine room from the passenger compartment, which partition wall may be constituted by a dashboard panel. This torque rod having one end connected to the power plant has the other end connected at right angles to the partition wall and, therefore, not only does it tend to exhibit insufficient strength, but also vibrations of the power plant tend to be readily and markedly transmitted to the passenger compartment thereby constituting one of the major causes of noises.
The Japanese Laid-open Utility Model Publication No. 54-5233, laid open to public inspection on Jan. 13, 1979, discloses a solution to the problem inherent in the employment of the torque rod discussed above. According to this prior art publication, the automobile power plant is supported at three points including first and second points of connection, each located between one respective end of the power plant and a respective side wall defining the associated tire housing and above the center of gravity of the power plant, and a third point of connection for the support of the power plant from below and located immediately below the center of gravity of the power plant as a whole. These points of connection are so positioned and so arranged that the center of gravity of the power plant inclusive of the engine, the transmission and the differential gear box substantially lies on and within the triangular plane defined by these points of connection, i.e., on and within the plane of triangular shape whose apexes are respectively occupied by the first to third points of connection.
Each of the first and second points of connection is defined by a respective elastically yieldable bearing structure disclosed as comprised of a generally U-shaped bracket secured to the respective side wall, and an elastic member carried by the bracket and connected to the power plant through a rigid tubular member, whereas the third point of connection is defined by a third elastically yieldable bearing structure disclosed as comprised of elastic members which are secured to the power plant through a bracket and a sub-frame through another bracket.
The prior art three-point support system is described as effective to minimize the rolling motion of the power plant without relaying on the use of such a torque rod as hereinbefore discussed. However, since it is essential for the third point of connection to be located immediately below the center of gravity of the power plant and the third elastic bearing structure is, therefore, responsible for the support of a majority of the entire weight of the power plant, the sub-frame has become necessitated. Although the above mentioned publication is silent as to the nature of the sub-frame and how it is associated with the automobile body structure, the sub-frame is shown as having a generally inverted U-shaped cross-section as viewed in a direction at right angles to the axis of rotation of the transversely mounted engine, i.e., in a direction longitudinally of the automobile, and accordingly, it appears reasonable to conclude that the sub-frame extends longitudinally of the automobile beneath the power plant and terminates in connected relation to the partition wall between the engine compartment and the passenger compartment. So far as the sub-frame is connected to the partition wall, i.e., the dashboard panel, vibrations generated from the power plant when in operation are after all transmitted through the sub-frame to the passenger compartment.